Parallel optical system with integrated monitoring photodetectors

The invention provides an optical system, in particular, a multi-channel parallel optical transceiver system with monitoring photodetectors and methods of forming the same. The multi-channel parallel optical system includes a substrate with at least one optical component mounted on the first side, at least one optical monitoring photodetector (mPD) fabricated on the first side of the substrate, a set of optical functional components disposed on the first side of the substrate to guide and reflect the light signal, an arrayed fiber placement structure fixing at least one optical fiber and having an exposed end to couple with the optical functional components to guide and diffract light from and to the optical components mounted on the first side of the substrate. The optical alignment of the optical placement structure, optical functional components, and the optical components mounted on the substrate is realized passively through the alignment holes and pins.